I have the same problem. Engine light keeps coming on and going off at different interval. I have not yet changed the O2 sensor and I would like to know if I can check the O2 sensor with a voltmeter or check the circuit but have no idea what values to look for.
My WJ surges right after starting, cold or hot engine makes no difference. When surging, putting tranny in N stops the surging and I have full throttle control with good response. I rev it up to 2500 Rpm a couple of times in N and the surging stops. Then it will not happen again even if driving for 500km. As soon as the engine is switched off, even just for a few minutes, the surging is happening again but not always. Sometimes I can drive for 2-3 days and no surging......
I changed the TPS, cleaned the ICV and throttle body and used some fuel cleaner and now I am using fuel injector cleaner.

1 Start the engine.
Allow the engine to idle for 4 to 5 minutes.
With the DRBIIIt, read the O2 Sensor voltage.
Is the voltage above 1.5 volts?
Yes ! Go To 2
No ! Go To 10

2 WARNING: WHEN THE ENGINE IS OPERATING, DO NOT STAND IN A
DIRECT LINE WITH THE FAN. DO NOT PUT YOUR HANDS NEAR THE
PULLEYS, BELTS OR FAN. DO NOT WEAR LOOSE CLOTHING.
Start the engine.
Disconnect the O2 Sensor harness connector.
With the DRBIIIt, monitor the O2 Sensor voltage.
Is the O2 Sensor voltage below 1.5 volts?
Yes ! Replace the O2 Sensor.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
No ! Go To 3

4 Turn the ignition off.
Disconnect the O2 Sensor harness connector.
NOTE: Two relays may be used on this vehicle for the different types of
Heated O2 Sensors. One uses the ASD Relay which is only used with PWM
O2 Sensor Heaters and the other uses the O2 Heater Relay.
Verify which relay is used to supply power for the O2 Sensor Heater being tested.
Measure the resistance between the O2 Sensor Signal circuit and the O2 Heater feed
circuit at the O2 Sensor harness connector.
Is the resistance below 5.0 ohms?
Yes ! Repair the O2 Sensor Signal circuit for a short to the O2 Heater
Feed circuit.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
No ! Go To 5

9 If there are no possible causes remaining, view repair.
Repair
Replace and program the Powertrain Control Module in accordance
with the Service Information.
Perform POWERTRAIN VERIFICATION TEST VER - 5.

10 NOTE: The conditions that set the DTC are not present at this time. The
following list may help in identifying the intermittent condition.
WARNING: WHEN THE ENGINE IS OPERATING, DO NOT STAND IN A
DIRECT LINE WITH THE FAN. DO NOT PUT YOUR HANDS NEAR THE
PULLEYS, BELTS OR FAN. DO NOT WEAR LOOSE CLOTHING.
With the engine running at normal operating temperature, monitor the DRBIIIt
parameters related to the DTC while wiggling the wiring harness. Look for parameter
values to change and/or a DTC to set.
Review the DRBIIIt Freeze Frame information. If possible, try to duplicate the
conditions under which the DTC was set.
Refer to any Technical Service Bulletins (TSB) that may apply.
Visually inspect the related wiring harness. Look for any chafed, pierced, pinched, or
partially broken wires.
Visually inspect the related wiring harness connectors. Look for broken, bent, pushed
out, or corroded terminals.
Were any of the above conditions present?
Yes ! Repair as necessary
Perform POWERTRAIN VERIFICATION TEST VER - 5.

dpshoup. truck runs fine ,no problems except the mil. from my code reader data that o2 reads 1.0 with no change. gona follow and wiggle harness on saturday when i have more time.also checking harness splices to see if anything frayed.